The present invention pertains generally to apparatuses for applying fluid material to panels and particularly to an apparatus capable of treating panels with irregular side edges.
In use for some years now are panels fabricated from wood waste including sawdust, chips, and random shaped and sized particles. Such panels are termed particle board in the wood products industry. During fabrication of the panels, the wood particulate with a binder is subjected to heat and pressure for the purpose of providing a panel of the density desired.
A demand presently exists for particle board suitable for use in exterior construction applications such as in building walls. A problem is encountered however when particle board is used exteriorly in that the fibrous nature of the particle board renders same susceptible to moisture absorption. Entry of moisture into any portion of the panel results in swelling of same and eventual panel deterioration with adverse effects being imparted to associated building components.
Various solutions have been tried without a great deal of success. While sealant may be suitably applied to the major or top and bottom planar faces of a particle board panel using conventional roll means, a particularly troublesome area to seal has been the tongue and groove side edges of a panel which edges are intended for mated engagement with adjacent panels. Failure to fully seal such an edge renders the panel susceptible to absorption which generally occurs in a gradual manner after panel installation and entailing substantial replacement effort and cost.
Efforts to remedy the problem by applying excessive sealant to the irregular panel edges interferes with the necessary nicety of fit during later mating of panel edges at a job site.
Further, the application of sealant to panel edges by spray application has not proved acceptable since such application does not adequately surface coat the panel nor physically impregnate sealant into the outer boundary area of the panel. The application of sealant by means of a curtain coater has also proved to provide less than acceptable sealant application.
Prior art of some interest includes U.S. Pat. Nos. 2,682,254 and 2,905,141, both disclosing a single adhesive carrying applicator roll having a peripheral surface shaped for light adhesive transferring contact with the finger shaped end of a piece of lumber to be end spliced. Such an arrangement is not suitable for the pressured application of a viscous liquid to the irregular sides of a panel wherein dimensional changes can occur. U.S. Pat. No. 2,811,133 discloses an apparatus for color coating a peripheral beveled edge of accoustical tile with no provision made for the remaining side surfaces. U.S. Pat. No. 3,875,897 discloses a lumber jointer and coater for trueing the edges of a lumber strip and thereafter applying glue to the edge by means of doctor and applicator rolls with no provision made for imparting viscous material to an irregular lumber side edge.